Index: src/mutators.cpp
===================================================================
--- src/mutators.cpp	(revision 471)
+++ src/mutators.cpp	(working copy)
@@ -151,10 +151,22 @@
 bool GET_bool( SEXP x, int index ){
 	switch( TYPEOF(x) ){
 		case INTSXP: 
+            if (INTEGER(x)[index] == R_NaInt) {
+                throwException( "NA boolean values not supported by RProtoBuf",
+                                "CastException" ) ;
+            }
 			return( (bool)INTEGER(x)[index] );
 		case REALSXP: 
+            if (REAL(x)[index] == R_NaReal) {
+                throwException( "NA boolean values not supported by RProtoBuf",
+                                "CastException" ) ;
+            }
 			return( (bool)REAL(x)[index] );
 		case LGLSXP:
+            if (LOGICAL(x)[index] == NA_LOGICAL) {
+                throwException( "NA boolean values not supported by RProtoBuf",
+                                "CastException" ) ;
+            }
 			return( (bool)LOGICAL(x)[index] );
 		case RAWSXP:
 			return( (bool)RAW(x)[index] ) ;
Index: inst/unitTests/runit.golden.message.R
===================================================================
--- inst/unitTests/runit.golden.message.R	(revision 471)
+++ inst/unitTests/runit.golden.message.R	(working copy)
@@ -60,9 +60,18 @@
 	test <- new(protobuf_unittest.TestAllTypes)
 	test$add("repeated_int32", c(1:5))
 	checkEquals(test$repeated_int32, c(1:5))
+}
 
-        # Prior to RProtoBuf v0.2.5, this was not handled properly.
-        test.2 <- new(protobuf_unittest.TestAllTypes,
-                      repeated_string=c("foo", "bar"))
-        checkEquals(test.2$repeated_string, c("foo", "bar"))
+test.repeated.bools <- function() {
+	test <- new(protobuf_unittest.TestAllTypes)
+        test$add("repeated_bool", c(TRUE, FALSE))
+        checkEquals(test$repeated_bool, c(TRUE, FALSE))
+
+        test$add("repeated_bool", as.integer(c(TRUE, FALSE)))
+        test$add("repeated_bool", as.numeric(c(TRUE, FALSE)))
+
+        checkEquals(test$repeated_bool, rep(c(TRUE, FALSE), 3))
+
+        # Verify that we don't silently cast NA into TRUE or FALSE.
+        checkException(test$add("repeated_bool"), c(TRUE, FALSE, NA))
 }